Facial recognition might be all the rage in giving computer systems the ability to ascertain the identity of individuals - what with most people having different facial features and all. But a team from the Hasso Plattner Institute in Potsdam, Germany, has taken a different approach to identify users of touch-based tabletop computers like Microsoft's Surface. Instead of focusing on the face, the team has looked in the opposite direction to develop a system known as Bootstrapper which distinguishes between users based on their footwear.